The research represents a continuation of our studies on the development of the employment of clustering as a mediational strategy in a free recall task. Children's recall performance, clustering behavior, as measured by the parameter X, retrieval time and introspective report are utilized to answer questions about the development of high level, mediational skills in children differing in age, race and socioeconomic status. Study 1 systematically explores the relationship among a series of dimensions characterizing the material to be learned and the use of the clustering strategy. The goal is to understand the developmental patterns of different groups of children. In addition, we examine the role of reorganizing the cues during the input and output stages of learning as a facilitator in the employment of the clustering strategy among children who do not spontaneously employ planned mediational learning strategies. Study 2 investigates the developmental role played by the ability to verbalize the clustering strategy. It is designed to test the relationship between the verbal expression of the principles involved in clustering and the behavior organized by those principles. In Study 3 the findings of the earlier studies are incorporated into a training program. This program recapitulates the developmental sequence in a long term series of training sessions geared to the level of the child.